The present invention relates to pre-treatment of cellulosic biomass feed stocks, such as agricultural residues (including stalks, stover and hulls), straws and grasses, forest and sawmill residues (including wood chips and shredded thinnings). In particular, the invention relates to pre-hydrolysis and steam explosion pretreatment to extract carbon sugars from the biomass feed stocks.
High pressures and/or high temperatures are typical in pre-treatments used to generate alcohols, e.g. ethanol, from cellulosic feed-stocks. In these conventional pre-treatments, some C5 sugars are converted to components which inhibit the alcohol fermentation of C6 sugars in the fermentation step following pre-treatment. Removing these inhibiting components, such as aldehydes (e.g., HMF, furfural, and formaldehyde), monomeric phenolics (e.g., vanillin and coniferylaldehyde), acids (e.g., formic acid) and other inhibitors should increase the alcohol yield in the C6 fermentation step following pretreatment.